1. Field of the Invention
The present invention relates to a vehicular lamp. More particularly, the present invention relates to a headlamp, a stop lamp, a tail lamp, a turn lamp, and the like used for a vehicle including automobiles, motorcycles and trains.
2. Related Art
A vehicular lamp employing a semiconductor light emitting device is known (e.g., Japanese Patent Laid-Open No. 2002-231014 bulletin (page 3–6, FIG. 1–13)). In general, the vehicular lamp has to be on stably for safety reasons.
However, if the excessive electric current flows in the semiconductor light emitting device, the life of the semiconductor light emitting device may become shorter due to heat generation. Therefore, for the vehicular lamp using a semiconductor light emitting device, it is desirable to control the current to the semiconductor element accurately.